1. Field of the Invention
The present invention relates to a header pipe to be used as a tank in a heat exchanger, a method for manufacturing the header pipe, and an apparatus for manufacturing the header pipe.
2. Description of the Related Art
Conventionally, in a heat exchanger such as a capacitor for use in a car or the like, for example, as disclosed in Japanese Utility Model Publication No. Hei. 4-63982, a partition is provided in a header to thereby change the flow passage of fluid.
And, conventionally, this type of header with a partition for use in a heat exchanger is manufactured in the following manner as shown in FIG. 36.
At first, an aluminum alloy pipe member with a brazing member clad on the outer surface thereof is cut to a given size to thereby obtain a pipe 11 which can be used in a header.
After then, in the pipe 11, there are formed a plurality of tube insertion holes 13, a slit for a divide 15, a fluid flow-in port 17, and a fluid flow-out port 19.
Next, an aluminum alloy divide 21 with brazing members clad on the two surfaces thereof is inserted into the slit for a divide 15, and also two aluminum alloy patches 23 are respectively pressure inserted into the two end portions of the pipe 11.
However, in the thus structured header with a partition for use in a heat exchanger, since there is used an expensive pipe member which has been previously formed in a cylindrical shape, the material cost thereof is high.
Also, there is a fear that a poor brazed condition can occur between the pipe 11 and divide 21.
Conventionally, as a method which has solved these problems, there is known a method for manufacturing a pipe with a partition which is disclosed in Japanese Patent Publication No. Hei. 7-314035 previously applied by the present applicants.
In this method for manufacturing a pipe with a partition, as shown in FIGS. 37 and 38, there is manufactured a pipe with a partition structured such that a partition portion 33 comprising a pair of semidivided partition portions 32 is formed in the central portion of a cylindrical-shaped pipe portion 31 thereof.
And, the present pipe with a partition can be manufactured in the following manner:
That is, at first, in a molding step shown in FIG. 39, a plate member formed of aluminum is molded in such a manner that a pair of semidivided cylindrical portions 35 are formed.
The pair of semidivided cylindrical portions 35 are arranged in parallel to each other with an arc-shaped connecting portion 37 between them.
And, each of the paired semidivided cylindrical portions 35 includes a partition forming portion 39 which projects inwardly in a U-shape manner.
Also, each of the paired semidivided cylindrical portions 35 is smaller by 2 mm or so in radius than a pipe portion 31 to be formed, while each semidivided cylindrical portion 35 further includes an edge portion 41 on the outside thereof.
The above-mentioned molding step is carried out by holding the aluminum flat plate between a given pair of metal molds and then molding the flat plate by pressing.
Next, in a cutting step shown in FIG. 40, a portion A of the connecting portion 37 situated between the partition forming portions 39 shown by oblique lines in FIG. 40 as well as the edge portions 41 respectively situated on the two sides of the partition portions 39 are cut and removed together with the excessively increased thickness portions 41a of the edge portions 41.
This cutting step is executed by trimming and piercing the press worked plate using a piece of press work machinery.
After then, in a compressing step shown in FIG. 41, the partition forming portion 39 is compressed from both sides thereof to thereby form a semidivided partition portion 32.
This compressing step is carried out in such a manner as shown in FIG. 42: that is, the outside portions of the semidivided cylindrical portions 35 are respectively held by a work holder 51 which is energized by springs 49 and, on the other hand, two compressing members 53 are respectively disposed on the two sides of the partition forming portion 39 located inwardly of the semidivided cylindrical portions 35, whereby the partition forming portion 39 is compressed in the direction of arrows B and molded by the compressing members 53.
In this compression molding operation, between the compressing members 53, there is interposed a dimension correcting block 55; that is, the inwardly projecting length H of the semidivided partition portion 32 can be corrected by the dimension correcting block 55.
Next, in an edge portion molding step shown in FIG. 43, the two edge portions 41 situated on the two sides of the pair of semidivided cylindrical portions 35 are molded, and the edge portions 41 are formed in an arc-shaped manner; that is, the edge portions 41 are so formed as to continue with their respective semidivided cylindrical portions 35 in an arc-shape manner.
This edge portion molding step is carried out by holding the pair of semidivided cylindrical portions 35 between a given metal molds and then molding them by pressing.
After then, according to a mutually opposing step shown in FIG. 44, the connecting portion 37 is projected from the inside thereof to thereby allow the pair of semidivided cylindrical portions 35 to be disposed in such a manner that they are opposed to each other.
In particular, this mutually opposing step is carried out by storing the outside portions of the semidivided cylindrical portions 35 into a metal mold 57 and then pressing the connecting portion 37 against the arc portion 61 of the metal mold 57 by a punch 59.
Next, according to a butting step shown in FIG. 45, the pair of mutually opposed semidivided cylindrical portions 35 are butted against each other.
This butting step can be carried out by storing the outside portions of the semidivided cylindrical portions 35 into a metal mold (not shown) and then moving the metal mold. In this step, the semidivided cylindrical portions 35 are molded into a pipe shape.
After then, a connecting step is carried out: that is, not only the pair of semidivided cylindrical portions 35 but also the pair of semidivided partition portions are connected to each other, thereby manufacturing a pipe with a partition which is shown in FIGS. 46 and 47.
The connecting step can be achieved, for example, by executing a brazing operation using non-corrosive flux.
Now, FIG. 46 shows a header with a partition for use in a heat exchanger manufactured in the above-mentioned conventional method for manufacturing a pipe with a partition; and, the present header with a partition for a heat exchanger includes a partition portion 33 formed in the central portion of a cylindrically-shaped pipe portion 31A thereof.
Also, on one side of the outer periphery of the pipe portion 31A, there are formed tube insertion holes 63 which are spaced from each other at given intervals.
Further, the openings of the pipe portion 31A, which are respectively formed in the two ends of the pipe portion 31A, are closed by cover members 65 respectively.
In the present method for manufacturing a header with a partition for a heat exchanger, after completion of the edge portion molding step shown in FIG. 43, as shown in FIG. 47, the tube insertion holes 63 are formed in one of the semidivided cylindrical portions 35 at given intervals and, at the same time, there are formed a fluid flow-in port 67, into which a thermal medium is allowed to flow, and a fluid flow-out portion 69 from which the thermal medium is allowed to flow out.
This step can be carried out by slit-pierce molding the semidivided cylindrical portion 35 using a piece of press work machinery.
In the thus manufactured header with a partition for use in a heat exchanger, since a single piece of plate member can be molded easily into a pipe portion 31A having a partition portion 33 formed integrally therewith, there is eliminated the need for use of an expensive pipe member which has been previously formed into a cylindrical shape. This makes it possible to reduce the material cost thereof greatly when compared with the previously cited conventional header.
Also, with use of the present header with a partition for use in a heat exchanger, when compared with the method in which a pipe is manufactured in a cylindrical shape, since the partition portion thereof is formed integrally with the pipe portion thereof, the number of parts used can be decreased to thereby be able to reduce the cost of the header.
Further, because the tube insertion hole 63 can be worked in a semicircle condition, a mold used to mold the tube insertion hole 63 can be made sufficiently strong, the working time of the tube insertion holes 63 can be shortened, and thus the cost of the header can also be reduced.
Also, since the pair of semidivided cylindrical portions 35 and the pair of semidivided partition portions 32 can be connected to each other positively by brazing, it is possible to surely prevent the thermal medium from leaking externally from the partition portion 33.
Next, another example of a method for manufacturing a pipe member, especially focused on the method for connecting edge portions of the cylindrical portions will be described. The pipe member according to the above method is manufactured in such a manner that, as shown in FIG. 50, a plate member 311 is molded into a cylindrical-shaped member and, after then, one side edge portion 311a of the cylindrical-shaped member and the other side edge portion 311b thereof are connected together by brazing R.
However, in such conventional pipe member 313, if the pipe member 313 is heated up to a high temperature within a brazing furnace for the purpose of brazing, then, as shown in FIG. 51, with a point C as the center thereof, one side edge portion 311a and the other side edge portion 311b are opened, which makes it difficult to braze together one side edge portion 311a and the other side edge portion 311b with accuracy.
In view of this, conventionally, as shown in FIG. 52, there is employed a method in which one side edge portion 311a and the other side edge portion 311b of the pipe member 313 are previously spot welded W together at intervals and, after then, one side edge portion 311a and the other side edge portion 311b are brazed to each other.
However, in the above-mentioned conventional manufacturing method, because one side edge portion 311a and the other side edge portion 311b of the pipe member 313 are previously spot welded W together at intervals, there arises a problem that a large number of man-hours are necessary to manufacture the pipe member 313.
Conventionally, as a method which has solved this problem, there are known a pipe and a method for manufacturing the same.
FIGS. 53 and 55 respectively show a pipe which adopts such method. This pipe is used as a tank for a heat exchanger such as a capacitor or the like and includes a pipe main body 321 on one side of which there is formed a partition portion 323 used to partition the passage of a refrigerant.
The pipe main body 321 is formed in a cylindrical shape, while two patch ends 325 each formed of aluminum are respectively fitted with and brazed to the two sides of the pipe main body 321.
One side edge portion 327 and the other side edge portion 329 of the pipe main body 321, as shown in FIG. 55, are brazed R to each other.
And, as shown in FIG. 54, in the longitudinal direction of the pipe main body 321, there are provided a plurality of fitting portions 331 which are spaced at intervals from one another.
Each of the fitting portions 331, as shown in FIG. 53, includes a securing portion 333 to be formed integrally with one side edge portion 327 of the pipe main body 321, and a caulking pawl portion 335 to be formed integrally with the other side edge portion 329 of the pipe main body 321.
And, the leading end portion 335a of the caulking pawl portion 335 is stored in a securing recessed portion 337 which is formed in the pipe main body 321.
Now, the above-mentioned pipe is manufactured in the following manner.
That is, at first, according to a molding step shown in FIG. 56, a flat plate formed of aluminum is molded to thereby form a pair of semicircular-shaped semidivided cylindrical portions 339.
The pair of semidivided cylindrical portions 339 are arranged in parallel to each other with an arc-shaped connecting portion 341 between them.
And, at the same time when the pair of semidivided cylindrical portions 339 are formed, in the respective edge portions of the pair of semidivided cylindrical portions 339, there are also formed flat portions 343 which project outwardly.
Also, at the same time when the pair of semidivided cylindrical portions 339 are formed, on the edge portion side of one of the pair of semidivided cylindrical portions 339, there is formed a securing recessed portion 337.
The above-mentioned molding step is executed by holding the flat plate between given metal molds and then molding the same by pressing.
Next, according to a bending step shown in FIG. 57, the flat portion 343 is bent in the opening direction of the semidivided cylindrical portion 339 being in a direction of the arrow C to thereby form a flange portion 345.
After then, according to a cutting step shown in FIG. 58, the flange portion 345 is cut and removed while the portion thereof corresponding to the securing recessed portion 337 is left, that is, the portions of the flange portion 345 shown by oblique lines in FIG. 58 are cut and removed; and, on the securing recessed portion 337 side, there is formed the securing portion 333.
Also, on the opposite side of the securing recessed portion 337, there is formed a caulking pawl portion forming portion 347.
This cutting step can be achieved by trimming the flat plate using a piece of press work machinery.
Next, according to a caulking pawl portion molding step shown in FIG. 59, the caulking pawl portion forming portion 347 is pushed outwardly by an amount correspond to the thickness of the flat plate to thereby form the-caulking pawl portion 335.
After then, according to a mutually opposing step shown in FIG. 60, the connecting portion 341 is projected from the inside thereof to thereby dispose the pair of semidivided cylindrical portions 339 in such a manner that they are substantially opposed to each other.
This mutually opposing step can be attained by storing the pair of semidivided cylindrical portions 339 into a metal mold (not shown) and then pressing the connecting portion 341 against the arc-shaped portion of the metal mold using a punch.
Finally, according to a curling step shown in FIG. 61, the pair of substantially opposed semidivided cylindrical portions 339 are butted against each other and, at the same time, the caulking pawl portion 335 is bent along the outside portion of the securing portion 333, so that the caulking pawl portion 335 is fitted with the securing portion 333.
This curling step is carried out in the following manner: that is, a pipe member 351 formed in such a manner as shown in FIG. 61 is stored in a pair of mutually opposed metal molds 353 and then the metal molds 353 are moved.
In both of the two metal molds 353, there are formed semicircular-shaped arc portions 355 and, in the edge portion of one of the metal molds 353, there is formed a curling portion 357.
And, curling can be achieved by moving both of the metal molds 353 at an angle of, for example, 10 degree, as shown by arrows D in FIG. 61.
That is, as shown in FIG. 62, after the leading end of the caulking pawl portion 335 is contacted with the wall portion 359 of the curling portion 357, if the metal molds 353 are closed further, then the caulking pawl portion 335 is curled along the securing portion 333, so that the caulking pawl portion 335 is fitted with the securing portion 333.
After then, according to a brazing step, not only one side edge portion 327 and the other side edge portion 329 are brazed to each other but also the securing portion 333 and caulking pawl portion 335 are brazed to each other.
This brazing step can be achieved in the following manner: that is, for example, non-corrosive flux is applied onto the brazing portions and, after then, the brazing portions are thermally treated in the nitrogen ambient condition.
With use of the pipe structured in the above-mentioned manner, if the securing portion 333 formed integrally with one side edge portion 327 of the pipe main body 321 is fitted with the caulking pawl portion 335 formed integrally with the other side edge portion 329 of the pipe main body 321, then one side edge portion 327 and the other side edge portion 329 can be positively contacted with each other at a given position; that is, without using spot welding or the like, one side edge portion 327 and the other side edge portion 329 can be positively connected with each other at a given position.
Also, since the leading end of the caulking pawl portion 335 is stored in the securing recessed portion 337 formed in the pipe main body 321, the caulking pawl portion 335 is prevented from projecting, which makes it possible to obtain a pipe which is free from troublesome projecting portions.
Further, in the above pipe, due to the fitting engagement between the securing portion 333 and caulking pawl portion 335, one side edge portion 327 and the other side edge portion 329 are positively contacted with each other at a given position, and such contact can be kept even if the temperature rises. Therefore, not only one side edge portion 327 and the other side edge portion 329 can be positively brazed to each other but also the securing portion 333 and caulking pawl portion 335 can be positively brazed to each other.
However, according to one of the above-mentioned conventional methods for manufacturing a header pipe with a partition for use in a heat exchanger, in the cutting step shown in FIG. 40, when the edge portions 41 respectively situated on the two sides of the partition forming portions 39 are cut and removed together with the excessively increased thickness portions 41a by trimming, then, as shown in FIG. 48, in each of the edge portions 41, there are produced loosened portions 41c and 41d in a trimmed or cut surface 41b thereof, so that the length of a linear portion 41e thereof is reduced. That is, when the pair of semidivided cylindrical portions 35 are butted against each other and are then brazed together, it is difficult to obtain a sufficient brazing strength, which in turn makes it difficult to secure a given cutting strength which is required of a header pipe.
By the way, the above-mentioned problem can also be solved by previously increasing the thickness of a flat plate serving as a blank material in consideration of production of the loosened portions 41c and 41d. However, in this case, there arises another problem that the material cost of the header pipe increases.
Further, in the butting step shown in FIG. 45, when the pair of semidivided cylindrical portions 35 are pressed and butted against each other by a pair of metal molds, as shown in FIG. 49, not only there are formed hollows 68 respectively on the two sides of the portion that was the connecting portion 37 in the mutually opposing step shown in FIG. 44, but also there is formed a projecting portion 70 in the central portion of the portion that was the connecting portion 37.
That is, when the two sides of the portion that was the connecting portion 37 are hollowed and, at the same time, the central portion of the portion that was the connecting portion 37 is projected, it is difficult to braze a pipe laying connector, a mounting bracket and the like in a positive manner.
The present inventors have studied deliberately the above-mentioned problem in order to solve the same. Our study has found why the two sides of the portion that was the connecting portion 37 are hollowed and, at the same time, the central portion of the portion that was the connecting portion 37 is projected; that is, the reason of occurrence of such hollows and projecting portion is that the molding or working properties of the connecting portion 37 in the molding step shown in FIG. 39 are revived.
Further, also in another of the above-mentioned conventional pipe manufacturing methods, there is still found a problem. That is, when the pair of mutually opposed semidivided cylindrical portions 339 are butted against each other to thereby mold them into a pipe shape in the curling step shown in FIG. 61, the outside surfaces of the semidivided cylindrical portions 339 are mainly pressed by the metal molds 353. At this time, it is impossible to dispose any member to regulate the position of the pair of mutually opposed semidivided cylindrical portions 339, therefore, it can be rotated in the metal molds 353. So there is possibility that the tip end of the caulking pawl portion 349 which is positioned closest to the opposed metal mold 353 is caused to collide with the outside portion of the metal mold 353 which is located outside of the actual working portion of the caulking pawl portion 349 in the metal mold 353, so the caulking pawl portion 349 is deformed outward. By this deformation, there is occurred a problem that the peripheral portion of the deformed caulking pawl portion 349 in the pipe is also deformed, or it becomes impossible to caulk the caulking pawl portion 349 to the securing recessed portion 337.